Cfrench:BALTIC

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BALTIC: BioBrick Assembly by Ligation of Triple-digested Components

This is a method for assembling two BioBricks, U (upstream) and D (downstream), without purifying fragments from a gel or using alternate vectors with different antibiotic resistance elements. It relies on digestion with a third enzyme cutting within the vector, so that each BioBrick is attached to a partial vector. The third enzyme can be ScaI, which cuts within the beta-lactamase gene of ampicillin-resistant vectors, or alternatively PvuI or SfiI; these enzymes will all work with pSB1A2 or pSB1A3. Obviously, the restriction site chosen must be absent from the sequence of both BioBricks. The protocol is as follows:

1. Digest BioBrick U:

38 microlitres water

2.5 microlitres DNA

5 microlitres buffer D (Promega) or 2 (New England)

1.5 microlitres SpeI

1.5 microlitres PstI

1.5 microlitres ScaI

TOTAL 50 microlitres

2. Digest BioBrick D:

38 microlitres water

2.5 microlitres DNA

5 microlitres buffer D or 2

1.5 microlitres EcoRI

1.5 microlitres XbaI

1.5 microlitres ScaI

TOTAL 50 microlitres

3. After several hours at 37 C, purify the DNA from both reactions using 5 microlitres of glass beads and elute to 10 microlitres of EB.